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32
33 The Mirror API is used to model the semantic structure of a program.
34 It provides representations of the entities
35 declared in a program, such as classes, methods, and fields.
36 Constructs below the method level, such as
37 individual statements and expressions, are not represented.
38
39 <p> Also included is support for writing
40 {@linkplain com.sun.mirror.apt.AnnotationProcessor annotation processors}
41 to examine and process the annotations
42 of program elements. An annotation processor may, as an example, create
43 new source files and XML documents to be used in conjunction with the
44 original code.
45
46
47 <h4> Characteristics of the API </h4>
48
49 A program is represented at the language level, rather than at the
50 level of the virtual machine. Nested classes, for example, are
51 handled as first-class constructs,
52 rather than in the translated form understood by the VM.
53 Both source code and compiled code (class files) may be modeled
54 in this way.
55
56 <p> Programs are modeled in their static, or build-time, form.
57 This differs from the {@linkplain java.lang.reflect reflection} API,
58 which provides run-time information about classes and objects.
59
60 <p> The API does not provide direct support for generating new code.
61
62
63 <h4> Declarations and Types </h4>
64
65 The mirror API represents program constructs principally through the
66 {@link com.sun.mirror.declaration.Declaration} interface
67 and its hierarchy of subinterfaces in the package {@link
68 com.sun.mirror.declaration}. A <tt>Declaration</tt> represents a
69 program element such as a package, class, or method.
70 The interface hierarchy is depicted
71 <a href="com/sun/mirror/declaration/package-tree.html"> here</a>.
72
73 <p> Types are represented by the {@link com.sun.mirror.type.TypeMirror}
74 interface and its hierarchy of subinterfaces in the
75 package {@link com.sun.mirror.type}. Types include primitive types,
76 class and interface types, array types, type variables, and wildcards.
77 The interface hierarchy is depicted
78 <a href="com/sun/mirror/type/package-tree.html"> here</a>.
79
80 <p> The API makes a clear distinction between declarations and types.
81 This is most significant for generic types, where a single declaration
82 can define an infinite family of types. For example, the declaration of
83 <tt>java.util.Set</tt> defines the raw type <tt>java.util.Set</tt>,
84 the parameterized type {@code java.util.Set<String>},
85 and much more. Only the declaration can be annotated, for example,
86 and only a type can appear in a method signature.
87
88 <p> A program being modeled may be incomplete, in that
89 it may depend on an unknown class or interface type.
90 This may be the result of a processing error such as a missing class file,
91 or perhaps the missing type is to be created by an annotation processor.
92 See {@link com.sun.mirror.type.DeclaredType} for information on
93 how such unknown types are handled.
94
95
96 <h4> Utilities and Tool Support </h4>
97
98 The {@link com.sun.mirror.util} package provides
99 utilities to assist in the processing of declarations and types.
100 Included is support for using the visitor design pattern when
101 operating on declaration and type objects.
102
103 <p> The {@link com.sun.mirror.apt} package supports the writing
104 of annotation processors. It provides the mechanism for them to
105 interact with an annotation processing tool.
106
107
108 @since 1.5
109
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